• Transistor as a switch or an amplifier
• Phototransistor to function as an alarm
• Capacitor to store and release electricity
• Transducer to create sounds from a timer
• Resistor codes
• A miniature light bulb to display voltage
• The inner workings of a switch
• Using batteries and resistors in series and parallel
• Creating sounds by the pressure of your finger
• Making a matchbox that beeps when you touch it

Meet the Author
Charles Platt is a Contributing Editor and regular columnist for Make: magazine, where he writes about electronics. He is the author of the highly successful introductory hands-on book, Make: Electronics, and Make: More Electronics. 

Platt was a Senior Writer for Wired magazine, and has written various computer books. As a prototype designer, he created semi-automated rapid cooling devices with medical applications, and air-deployable equipment for first responders. He was the sole author of four mathematical-graphics software packages, and has been fascinated by electronics since he put together a telephone answering machine from a tape recorder and military-surplus relays at age 15. He lives in a Northern Arizona wilderness area, where he has his own workshop for prototype fabrication and projects that he writes about for Make: magazine.